Rukkwamsuk T, Kruip T A, Meijer G A, Wensing T
Department of Large Animal Medicine and Nutrition, Graduate School of Animal Health, Faculty of Veterinary Medicine, Utrecht University, The Netherlands.
J Dairy Sci. 1999 Feb;82(2):280-7. doi: 10.3168/jds.S0022-0302(99)75234-3.
The present study compared the hepatic fatty acid composition of cows that were fed a high energy diet during the dry period to induce fatty liver after parturition with that of control cows. Treated cows had higher concentrations of plasma nonesterified fatty acids as a result of greater lipolysis after parturition than did control cows; consequently, the treated cows accumulated greater amounts of triacylglycerols in the liver. Before parturition, treated cows had lower percentages of oleic acid and higher percentages of linoleic acid than did control cows, but percentages of other fatty acids were similar for both groups. After parturition, percentages of each fatty acid were changed substantially, particularly the four major fatty acids (palmitic, stearic, oleic, and linoleic acids). For treated cows, the percentages of palmitic and oleic acids were higher at 0.5 wk after parturition than at 1 wk before parturition; percentages of stearic and linoleic acids decreased. Unlike treated cows, the percentages of both oleic and linoleic acids in the control cows did not change during that time. Moreover, we found that when lipolysis decreased, as indicated by lower plasma nonesterified fatty acid concentrations, the percentages of each fatty acid gradually rebounded toward the concentrations measured before parturition; this observation indicates that the shift in hepatic fatty acid composition is influenced by lipolysis. The increased lipolysis after parturition led to a vast increase in the hepatic triacyglycerol concentration and to a shift in hepatic fatty acid composition.
本研究比较了干奶期饲喂高能日粮以诱导产后脂肪肝的奶牛与对照奶牛的肝脏脂肪酸组成。与对照奶牛相比，处理组奶牛产后脂肪分解增加，血浆非酯化脂肪酸浓度更高；因此，处理组奶牛肝脏中积累了更多的三酰甘油。产前，处理组奶牛的油酸百分比低于对照奶牛，亚油酸百分比高于对照奶牛，但两组其他脂肪酸的百分比相似。产后，每种脂肪酸的百分比发生了显著变化，尤其是四种主要脂肪酸（棕榈酸、硬脂酸、油酸和亚油酸）。对于处理组奶牛，产后0.5周时棕榈酸和油酸的百分比高于产前1周；硬脂酸和亚油酸的百分比下降。与处理组奶牛不同，对照奶牛在这段时间内油酸和亚油酸的百分比均未发生变化。此外，我们发现，当血浆非酯化脂肪酸浓度降低表明脂肪分解减少时，每种脂肪酸的百分比逐渐回升至产前测量的浓度；这一观察结果表明肝脏脂肪酸组成的变化受脂肪分解的影响。产后脂肪分解增加导致肝脏三酰甘油浓度大幅增加，并导致肝脏脂肪酸组成发生变化。
